3GPP (3rd Generation Partnership Project) is a project for discussing and preparing specifications of cellular telephone systems based on networks of evolved W-CDMA (Wideband-Code Division Multiple Access) and GSM (Global System for Mobile Communications). In 3GPP, the W-CDMA system has been standardized as the 3rd-generation cellular mobile communication system, and its service is started sequentially. Further, HSDPA (High-Speed Downlink Packet Access) with further increased communication rates has also been standardized, and its service is started. 3GPP is discussing evolution of the 3rd-generation radio access technique (Evolved Universal Terrestrial Radio Access: hereinafter, referred to as “EUTRA”).
As a downlink communication system in EUTRA, proposed is an OFDMA (Orthogonal Frequency Division Multiple Access) system for multiplexing users using mutually orthogonal subcarriers. Further, in the OFDMA system are applied techniques such as an adaptive modulation/demodulation-error correcting scheme (AMCS: Adaptive Modulation and Coding Scheme) based on adaptive radio link control (Link Adaptation) such as channel coding, etc. AMCS is a scheme for switching between radio transmission parameters (hereinafter, referred to as an “AMC mode”) such as an error correcting scheme, coding rate of error correction, the level of data modulation, etc. corresponding to channel quality of each mobile station apparatus so as to efficiently perform high-speed packet data transmission. The channel quality of each mobile station apparatus is sent back to the base station apparatus using CQI (channel Quality indicator) as feedback.
In OFDMA, it is possible to divide the communicable region into the frequency domain physically corresponding to subcarriers and time domain. A combination of some divided regions is referred to as a resource block, one or more resource blocks are allocated to each mobile station apparatus, and communications are performed while multiplexing a plurality of mobile station apparatuses. In order that the base station apparatus and each mobile station apparatus perform communications with optimal quality and rate in response to the request, required is physical resource block allocation and transmission scheme determination with consideration given to the channel quality of a frequency band associated with each subcarrier in each mobile station apparatus. Since the base station apparatus determines the transmission scheme and scheduling, to achieve the request, each mobile station apparatus gives feedback of channel quality for each frequency region to the base station apparatus. Further, when necessary, each mobile station apparatus transmits information indicative of a frequency region (for example, with good channel quality) selected by the mobile station apparatus to the base station apparatus as feedback.
Further, in EUTRA, to increase communication path capacity, it has been proposed to use transmission diversity such as SDM (Space Division Multiplexing), SFBC (Space-Frequency Block Diversity) and CDD (Cycle Delay Diversity) using MIMO (Multiple Input Multiple Output). MIMO is a generic name for Multiple Input Multiple Output systems or techniques, and is characterized in that a plurality of branches is used in input and output of radio signals to transmit, using a plurality of antennas on the transmission and reception sides. A unit of a signal sequence is referred to as a stream that can be transmitted in space multiplexing using the MIMO scheme. The number (Rank) of streams in MIMO communications is determined by the base station apparatus in consideration of channel state. The number (Rank) of streams requested by the mobile station apparatus is sent to the base station apparatus from the mobile station apparatus as feedback using RI (Rank Indicator).
Meanwhile, in using SDM on downlink, in order to accurately divide information of a plurality of streams transmitted from respective antennas, it is under review to perform preprocessing on a transmission signal sequence in advance (which is referred to as “precoding”). The information of precoding can be calculated based on channel state estimated by a mobile station apparatus, and the mobile station apparatus gives feedback to the base station apparatus using PMI (Precoding Matrix Indicator).
Thus, in order to achieve communications of optimal quality, each mobile station apparatus is required to transmit various kinds of information indicative of channel state to the base station apparatus as feedback. This channel feedback report CFR (channel state information) is formed of CQI, PMI, RI, etc. The number of bits and format of these channel feedback reports are designated from the base station apparatus to mobile station apparatuses corresponding to circumstances.
FIG. 15 is a diagram illustrating a channel structure in EUTRA (see Non-patent Document 1). The downlink of EUTRA is comprised of a physical broadcast channel (PBCH), physical downlink control channel (PDCCH), physical downlink shared channel (PDSCH), physical multicast channel (PMCH), physical control format indicator channel (PCFICH), and physical Hybrid ARQ indicator channel (PHICH).
Meanwhile, the uplink of EUTRA is comprised of a physical uplink shared channel (PUSCH), physical random access channel (PRACH), and physical uplink control channel (PUCCH).
In EUTRA, due to the nature of uplink single carrier, the mobile station apparatus cannot transmit signals concurrently using different channels (for example, PUSCH and PUCCH). When the mobile station apparatus transmits these channels at the same timing, the mobile station apparatus multiplexes the information using the definition of specifications, etc. to transmit on the determined channel, or transmits only either one of information according to the definition of specifications, etc. (does not transmit (drops) the other data).
Meanwhile, the PUSCH is mainly used to transmit uplink data, and the channel feedback report CFR is also transmitted using the PUSCH together with uplink data (UL-SCH) when the report is not transmitted using the PUCCH. In other words, the channel feedback report CFR is transmitted to the base station apparatus using the PUSCH or PUCCH. Generally, within a subframe, the PUSCH is assigned greater resources allocated to transmit the channel feedback report CFR than in the PUCCH, and enables transmission of more detailed channel feedback report CFR (when the number of physical resource blocks supported by the base station apparatus and mobile station apparatus is 65 to 110 (system bandwidth of 20 MHz), information of about 20 to 100 bits or more.) The mobile station apparatus can transmit information of only about 15 bits or less in a subframe using the PUCCH.
The mobile station apparatus is able to transmit the channel feedback report CFR periodically using the PUCCH. Further, the mobile station apparatus is able to transmit the channel feedback report CFR periodically or aperiodically using the PUSCH (Non-patent Documents 1 and 2). The base station apparatus sets persistent or permanent resources and transmission interval of the PUSCH on a mobile station apparatus using RRC signaling (Radio Resource control signal), and enables the mobile station apparatus to transmit the channel feedback report CFR periodically using the PUSCH. Further, by including a single bit of information for instructions for channel feedback report request (channel state report trigger) in an uplink transmission grant signal, the base station apparatus enables the mobile station apparatus to transmit the channel feedback report CFR and uplink data aperiodically (temporarily, in one shot) using the PUSCH.
Further, the mobile station apparatus is able to transmit only the channel feedback report CFR aperiodically using the PUSCH. Transmission of only the channel feedback report CFR is that the mobile station apparatus transmits only the channel feedback report CFR to the base station apparatus (where information of ACK/NACK, etc. is included), instead of concurrently transmitting the uplink data and channel feedback report CFR.
Meanwhile, in EUTRA, persistent or permanent PUSCH resources are scheduled for real-time traffic such as voice communications, and the mobile station apparatus is capable of transmitting the PUSCH for uplink data without an uplink transmission grant signal by PDCCH. This is called persistent scheduling. The base station apparatus sets transmission intervals on the mobile station apparatus using RRC signaling (Radio Resource Control signal), and activates persistent PUSCH allocation using a specific PDCCH. This specific PDCCH includes information for specifying a persistent PUSCH resource block, modulation and coding scheme, etc.